Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 60 users online :: 5 registered, 0 hidden and 55 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

chamber volume question

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
Sponsored 
  • Author
    Message

chamber volume question

Unread postAuthor: ilovefire » Wed Aug 25, 2010 2:40 am

sorry if this is a bit of an annoying question but i am making a coax with a 5mm bore and 50cm barrel and want to know what would be a good chamber volume be for say a max of 400psi and maybe a min of 300psi, i would like power but i only have a shock pump so ill need to take that into consideration
thanks
  • 0

User avatar
ilovefire
Colonel
Colonel
 
Posts: 511
Joined: Sat May 22, 2010 6:48 am
Reputation: 0

Unread postAuthor: MrCrowley » Wed Aug 25, 2010 4:40 am

Probably something as small as a 20mm tube 100mm long would suffice. I would GGDT it, but I'm busy at the moment. Perhaps you can try GGDT it yourself?

P.S - GGDT (gas gun design tool) is a tool developed by D_Hall (a member on spudfiles) to model guns in the designing stage to see how they would perform in real life. Check the Spudwiki for more info or google "GGDT" and check out his website (complete with FAQ section and such).
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: ilovefire » Wed Aug 25, 2010 4:53 am

MrCrowley wrote:Probably something as small as a 20mm tube 100mm long would suffice. I would GGDT it, but I'm busy at the moment. Perhaps you can try GGDT it yourself?

P.S - GGDT (gas gun design tool) is a tool developed by D_Hall (a member on spudfiles) to model guns in the designing stage to see how they would perform in real life. Check the Spudwiki for more info or google "GGDT" and check out his website (complete with FAQ section and such).


thank you for your help, i did look into it a bit but dose it work on a mac?

edit: sorry sould have looked before i posted, found the answer
  • 0

User avatar
ilovefire
Colonel
Colonel
 
Posts: 511
Joined: Sat May 22, 2010 6:48 am
Reputation: 0

Unread postAuthor: MrCrowley » Wed Aug 25, 2010 5:00 am

Hmm doesn't seem that way:
Are you ever gonna release a version for the Macintosh?
No. GGDT is a hobby; nothing more. I have made exactly zero dollars and zero cents for all the work I've put into it. With motivation like that, I don't see the point in buying a new computer just so I can do the port and make a few folks happy. What you CAN do, however, is run a Windows emulator on your Macintosh. There's a free one called "Guest PC." Feel free to download it.


Running a few rough coaxial piston valved launchers in GGDT using your barrel, 400PSI, a 20mmx100mm chamber, 2cm piston and an air rifle pellet I get about 285m/s, if you double the chamber size you get a few extra m/s in performance. From a rough calculation, a chamber 20mmx100mm seems fairly effecient.
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: ilovefire » Wed Aug 25, 2010 5:12 am

MrCrowley wrote:Hmm doesn't seem that way:
Are you ever gonna release a version for the Macintosh?
No. GGDT is a hobby; nothing more. I have made exactly zero dollars and zero cents for all the work I've put into it. With motivation like that, I don't see the point in buying a new computer just so I can do the port and make a few folks happy. What you CAN do, however, is run a Windows emulator on your Macintosh. There's a free one called "Guest PC." Feel free to download it.


Running a few rough coaxial piston valved launchers in GGDT using your barrel, 400PSI, a 20mmx100mm chamber, 2cm piston and an air rifle pellet I get about 285m/s, if you double the chamber size you get a few extra m/s in performance. From a rough calculation, a chamber 20mmx100mm seems fairly effecient.


thank you very much for your help and patience you have helped me alot :)
  • 0

User avatar
ilovefire
Colonel
Colonel
 
Posts: 511
Joined: Sat May 22, 2010 6:48 am
Reputation: 0

Unread postAuthor: MrCrowley » Wed Aug 25, 2010 5:18 am

For aesthetic or ergonomic reasons you may make the chamber bigger or longer or both, just letting you know that a chamber only 20mmx100mm big, is big enough to get some pretty decent performance.
If you doubled the barrel length but kept everything else the same, you could get around 330m/s (though take this with a grain of salt as I believe GGDT can run in to a few problems around the 'subsonic approaching supersonic' area). No doubt you'll see a huge increase in performance over the 50cm barrel though.
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: ilovefire » Wed Aug 25, 2010 5:35 am

MrCrowley wrote:For aesthetic or ergonomic reasons you may make the chamber bigger or longer or both, just letting you know that a chamber only 20mmx100mm big, is big enough to get some pretty decent performance.
If you doubled the barrel length but kept everything else the same, you could get around 330m/s (though take this with a grain of salt as I believe GGDT can run in to a few problems around the 'subsonic approaching supersonic' area). No doubt you'll see a huge increase in performance over the 50cm barrel though.


you have just answered some of the other questions that i had without me even having to ask them, you dont know just how grateful i am that there is someone willing to go out of there way to help a stranger
thank you :P
  • 0

User avatar
ilovefire
Colonel
Colonel
 
Posts: 511
Joined: Sat May 22, 2010 6:48 am
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: MrCrowley » Wed Aug 25, 2010 5:46 am

you dont know just how grateful i am that there is someone willing to go out of there way to help a stranger

I don't mind helping out someone from across the ditch, you aussies need all the help you can get :wink:
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: Crna Legija » Wed Aug 25, 2010 6:36 am

Only if you would run for PM :lol:
  • 0

'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson

Add me on ps3: wannafuk, 8/11/11 cant wait
User avatar
Crna Legija
Major General
Major General
 
Posts: 2333
Joined: Sun Jul 20, 2008 5:14 am
Location: australia
Reputation: 0

Unread postAuthor: ilovefire » Wed Aug 25, 2010 7:25 am

-_- wrote:Only if you would run for PM :lol:


yea that whole thing is a mess, glad i dont have to vote :lol:

oh and would a 10mm x 450mm chamber be able to get me that 280m/s?
thanks, it would be a great help
  • 0

User avatar
ilovefire
Colonel
Colonel
 
Posts: 511
Joined: Sat May 22, 2010 6:48 am
Reputation: 0

Unread postAuthor: chinnerz » Wed Aug 25, 2010 7:26 am

-_- wrote:Only if you would run for PM :lol:


Made me lol


Any ways isn't the rule for chamber volume no less then half or more than double the barrel volume?? Could have sworn that was the rule :/
  • 0

Image
User avatar
chinnerz
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 470
Joined: Mon Dec 28, 2009 8:08 am
Reputation: 0

Unread postAuthor: ilovefire » Wed Aug 25, 2010 7:34 am

chinnerz wrote:
-_- wrote:Any ways isn't the rule for chamber volume no less then half or more than double the barrel volume?? Could have sworn that was the rule :/


i once used my pen gun to shoot a ball bearing of of 5mm x 900mm barrel a 400psi mind you it probly didnt have any major power but it went pretty far
  • 0

User avatar
ilovefire
Colonel
Colonel
 
Posts: 511
Joined: Sat May 22, 2010 6:48 am
Reputation: 0

Unread postAuthor: MrCrowley » Wed Aug 25, 2010 3:16 pm

oh and would a 10mm x 450mm chamber be able to get me that 280m/s?
thanks, it would be a great help

Yup, GGDT says so.
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'